1. Field of the Invention
The present invention relates to a control device for an internal combustion engine.
2. Description of the Related Art
In cold engine starting, it is desirable that a catalytic device arranged in the exhaust system is warmed up immediately to purify the exhaust gas soon after the engine starts. To make a catalytic device be warmed up immediately, it is suggested to make an engine speed increased rapidly at the engine starting converge at a target engine speed by retarding of an ignition time. (For example, refer to Japanese Unexamined Patent Publication Nos. 2003-254141 and 2001-90581.)
In the above art, the ignition time is retarded so that the temperature of the exhaust gas increases to promote the warming-up of the catalytic device. Further, if the engine speed is still higher than the target engine speed when the ignition time has been retarded to the target ignition time, an amount of intake air is decreased so as to make the engine speed converge on the target engine speed.
By the way, according to an individual difference of engines, the engine speed may converge at the target engine speed before the ignition time is retarded to the target ignition time. At this case, in the above art, the ignition time is more advanced than the target ignition time so that the temperature of the exhaust gas does not increase sufficiently, and thus the catalytic device cannot be warmed up immediately.